What factors affect the catalytic effect of carbon monoxide catalysts?

The catalytic effect of carbon monoxide catalyst is affected by many factors, as follows:
Catalyst property
Active component: It is the key component of the catalyst. The catalytic activity of different active components for carbon monoxide is different. Precious metals such as platinum (Pt), palladium (Pd), rhodium (Rh), etc., have high activity and selectivity for carbon monoxide oxidation. Transition metal oxides such as copper oxide (CuO), manganese dioxide (MnO₂), etc., are lower cost but relatively weak activity. The content of active components will also affect the catalytic effect, generally within a certain range, the increase of content, catalytic activity is enhanced, but too high may lead to agglomeration, reduce the number of active sites, and make the catalytic effect worse.
Carrier: Supports the active component, affecting its dispersion and stability. Carriers with a high specific surface area, such as alumina (Al₂O₃), silicon dioxide (SiO₂) and activated carbon, can make the active components highly dispersed, increase the chance of contact with carbon monoxide, and improve the catalytic effect. The interaction between the carrier and the active component is also very important, and moderate interaction can stabilize the active component and enhance the catalytic performance. If the interaction is too strong or too weak, it will reduce the activity of the active component or lead to its loss.
The crystal structure and surface properties of the catalyst: the crystal structure determines the arrangement and distribution of the active site and affects the adsorption and reaction of carbon monoxide molecules. Adsorption and activation of reactants are affected by the properties of surface acid-alkalinity and oxidation-reduction. The surface acidic sites are conducive to the adsorption of some carbon-containing intermediate species, and the surface has appropriate oxidation-reduction properties, which is conducive to the oxidation of carbon monoxide.
Reaction condition
Temperature has a significant effect on the catalytic reaction rate. When the temperature is too low, the activity of carbon monoxide molecule and catalyst active site is low, and the reaction rate is slow. With the increase of temperature, the molecular thermal movement is accelerated, the contact chance between reactants and active sites is increased, and the reaction rate is accelerated. However, if the temperature is too high, the active component of the catalyst may volatilize, sintering or change the crystal structure, resulting in decreased activity. Each catalyst has its optimal activity temperature range, such as some precious metal catalysts at 200-300 ℃ for carbon monoxide catalytic oxidation effect is the best.
Pressure: Changes the adsorption and desorption balance of reactants on the catalyst surface. The adsorption amount of carbon monoxide and other reactants on the catalyst surface can be increased by increasing the pressure appropriately, and the reaction rate can be accelerated. However, too high pressure will increase equipment costs and safety risks, and may lead to side reactions, affecting the catalytic effect.
Gas composition: In addition to carbon monoxide in the reaction gas, other gas components will affect the catalytic effect. Oxygen is the reactant of carbon monoxide oxidation reaction, and appropriate amount of oxygen can promote the reaction. However, the oxygen content is too high, which may occupy too many active sites and inhibit carbon monoxide adsorption. In addition, impurities in the gas, such as sulfur, phosphorus, chlorine and other compounds, are easily adsorbed at the active site of the catalyst, resulting in catalyst poisoning and significantly reducing catalytic activity.